The majority of bariatric surgery patients have clinically significant obstructive sleep apnoea (OSA) but report fewer symptoms than other sleep disorder patients, according to a study published in the journal Sleep and Breathing.

“Patients with obstructive sleep apnoea frequently complain of sleepiness during the daytime, loss of motivation and interest in activities, as well as poor concentration and memory recall,” said lead author, Dr Katherine M Sharkey, department of medicine, division of pulmonary, critical care and sleep medicine at Rhode Island Hospital, and University Medicine. “The aim of this study was to evaluate associations between OSA severity and self-reported sleepiness and daytime functioning in patients considering bariatric surgery.”

The study identified 269 patients (239 of which were women) who had who had overnight polysomnography and completed the Epworth Sleepiness Scale (ESS) and the Functional Outcomes of Sleep Questionnaire (FOSQ) prior to bariatric surgery. The mean age of the patients was 42.0 ± 9.5 years and the mean BMI 50.2 ± 7.72. The patient’s OSA was classified as none/mild (apnoea-hypopnea index (AHI) <15), moderate (AHI 15-30) or severe (AHI≥30).

The researchers then calculated the proportion of unique variance for the five FOSQ subscales. Analysis of variance was used to determine if ESS and FOSQ were associated with OSA severity and unpaired t tests compared ESS and FOSQ scores in the study sample with published data.

Results

The outcomes revealed that the average AHI was 29.5 ± 31.5 events per hour (range = 0–175.8), the mean ESS score was 6.3 ± 4.8, and the mean global FOSQ score was 100.3 ± 18.2. The proportion of unique variances for FOSQ subscales showed moderate-to-high unique contributions to FOSQ variance, whilst ESS and global FOSQ score did not differ by AHI group.

One hundred and twelve patients were classified with none/mild AHI, 77 patients with moderate AHI and 80 patients with severe AHI. Therefore, 58.3% of patients had moderate or severe OSA that had not been diagnosed prior to the patients' evaluation in anticipation of bariatric surgery.

Although subjective sleepiness and functional impairment were not associated significantly with OSA severity, the researchers found that the vast majority of patients considering bariatric surgery for treatment of obesity have clinically significant OSA.

Despite the high prevalence of sleep apnoea, this sample of patients reported less sleepiness and daytime impairment than previously reported studies.

“These patients also report fewer symptoms and may be attributing daytime napping and decreased functioning to something other than a sleep disorder,” said Sharkey.

Sharkey warned that patients with severe obesity need evaluation for OSA as they under-report symptoms and self-report measures are not an adequate substitute for objective assessment and clinical judgment when evaluating bariatric patients for OSA.

“The lack of symptoms of sleep apnoea in this population means that we must be even more vigilant in identifying sleep apnoea prior to bariatric surgery in order to reduce the risk of complications,” she added. “Further research is needed to understand individual differences in sleepiness in patients with OSA.”

The study was supported by internal funding. Additional researchers involved in the study were Drs Richard P Millman, G Dean Roye, David Harrington and Christine Tosi, as well as Dr Henry J Orff, University of California at San Diego.

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